I was diagnosed with multiple (over 20) both immediate and delayed allergies over 10 years ago. What I know to be true from over 10 years of experience: doctors don't know anything about our bodies and brains. They know nothing, zero, nada.
The first thing I would like to say is food allergy symptoms can not only occur in 0 to 72 hours from eating the food. They can also cause foods that one isn't particularly allergic to, to cause more severe symptoms during the next week. "Got a reaction 24h after eating parsley", "the next week strawberries are going to itch my throat a lot more than usual".
The second thing is, the symptoms can change as you grow older. In my case, they began as 10-60 minute diarrhea episodes and shock (nausea, fast and irregular heartbeat). Now, 10 years later they can last from 15 minutes to six hours, no diarrhea, but all the symptoms of shock plus far more mental aspects of shock (nonspecific/overal feelings of fear, pain, confusion etc). To describe the feeling of fear shock causes, I say it's like when you were little, you were scared by dark and your imagination caused you to be even more scared. It feels like that, only this time you are consciously aware that there is no reason to be fearful, but your body still fears.
The third thing is, food allergy can affect hormone balance. I am a man who has a high sex drive, yet sometimes among other allergy symptoms, I can temporarily lose almost all my sex drive, I will not get the morning erections and so on. What is strange is, this sort of thing is usually caused by stress and/or depression, but when it is allergy related, there doesn't need to be any stress or depression.
The fourth thing is, the amount of allergy causing food often has no relation whatsoever to the severity of the symptoms.
Fifth, there is medicine that will help allergy symptoms; you just don't think of it as medicine. A high amount of caffeine can noticeably help the symptoms, including pollen allergy symptoms, and by high I mean half a liter (16 oz) of Coke. And even eating something like a sandwich, even when you don't feel like you could eat, will help the symptoms. I think the reason is, your brain's thinking goes like this: "something is seriously wrong.. wait he/she is eating, false alarm, move on".
Sixth, the symptoms may not include any stomach ache and/or airways tightening, but still there can be breathing difficulties and problems in the circulatory system.
Last, one can live a normal life with allergies like these. you just have to avoid the problematic foods, and when symptoms occur, remind yourself that it is just an allergy and there is no need to worry about things even when your body says you should worry about things.